package com.yls.except.util.imgfile;

import java.awt.image.BufferedImage;  

public class ScaleImage {  
    private int width;  
  
    private int height;  
  
    private int scaleWidth;  
  
    private double support = (double) 3.0;  
  
    private double PI = (double) 3.14159265358978;  
  
    private double[] contrib;  
  
    private double[] normContrib;  
  
    private double[] tmpContrib;  
  
    private int nDots;  
  
    private int nHalfDots;  
  
    /** 
     * Start: Use Lanczos filter to replace the original algorithm for image 
     * scaling. Lanczos improves quality of the scaled image modify by :blade 
     */  
    private static ScaleImage instance = new ScaleImage();  
    private ScaleImage(){};  
    public static ScaleImage getInstance(){  
        return instance;  
    }  
    public BufferedImage imageZoomOut(BufferedImage srcBufferImage, int w, int h) {  
        width = srcBufferImage.getWidth();  
        height = srcBufferImage.getHeight();  
        scaleWidth = w;  
  
        if (DetermineResultSize(w, h) == 1) {  
            return srcBufferImage;  
        }  
        CalContrib();  
        BufferedImage pbOut = HorizontalFiltering(srcBufferImage, w);  
        BufferedImage pbFinalOut = VerticalFiltering(pbOut, h);  
        return pbFinalOut;  
    }  
  
    /** 
     * 决定图像尺寸 
     */  
    private int DetermineResultSize(int w, int h) {  
        double scaleH, scaleV;  
        scaleH = (double) w / (double) width;  
        scaleV = (double) h / (double) height;  
        // �?��判断�?��scaleH，scaleV，不做放大操�?  
        if (scaleH >= 1.0 && scaleV >= 1.0) {  
            return 1;  
        }  
        return 0;  
  
    } // end of DetermineResultSize()  
  
    private double Lanczos(int i, int inWidth, int outWidth, double Support) {  
        double x;  
  
        x = (double) i * (double) outWidth / (double) inWidth;  
  
        return Math.sin(x * PI) / (x * PI) * Math.sin(x * PI / Support)  
                / (x * PI / Support);  
  
    } // end of Lanczos()  
  
    //    
    // Assumption: same horizontal and vertical scaling factor  
    //    
    private void CalContrib() {  
        nHalfDots = (int) ((double) width * support / (double) scaleWidth);  
        nDots = nHalfDots * 2 + 1;  
        try {  
            contrib = new double[nDots];  
            normContrib = new double[nDots];  
            tmpContrib = new double[nDots];  
        } catch (Exception e) {  
            System.out.println("init   contrib,normContrib,tmpContrib" + e);  
        }  
  
        int center = nHalfDots;  
        contrib[center] = 1.0;  
  
        double weight = 0.0;  
        int i = 0;  
        for (i = 1; i <= center; i++) {  
            contrib[center + i] = Lanczos(i, width, scaleWidth, support);  
            weight += contrib[center + i];  
        }  
  
        for (i = center - 1; i >= 0; i--) {  
            contrib[i] = contrib[center * 2 - i];  
        }  
  
        weight = weight * 2 + 1.0;  
  
        for (i = 0; i <= center; i++) {  
            normContrib[i] = contrib[i] / weight;  
        }  
  
        for (i = center + 1; i < nDots; i++) {  
            normContrib[i] = normContrib[center * 2 - i];  
        }  
    } // end of CalContrib()  
  
    // 处理边缘  
    private void CalTempContrib(int start, int stop) {  
        double weight = 0;  
  
        int i = 0;  
        for (i = start; i <= stop; i++) {  
            weight += contrib[i];  
        }  
  
        for (i = start; i <= stop; i++) {  
            tmpContrib[i] = contrib[i] / weight;  
        }  
  
    } // end of CalTempContrib()  
  
    private int GetRedValue(int rgbValue) {  
        int temp = rgbValue & 0x00ff0000;  
        return temp >> 16;  
    }  
  
    private int GetGreenValue(int rgbValue) {  
        int temp = rgbValue & 0x0000ff00;  
        return temp >> 8;  
    }  
  
    private int GetBlueValue(int rgbValue) {  
        return rgbValue & 0x000000ff;  
    }  
  
    private int ComRGB(int redValue, int greenValue, int blueValue) {  
  
        return (redValue << 16) + (greenValue << 8) + blueValue;  
    }  
  
    // 行水平滤�?  
    private int HorizontalFilter(BufferedImage bufImg, int startX, int stopX,  
            int start, int stop, int y, double[] pContrib) {  
        double valueRed = 0.0;  
        double valueGreen = 0.0;  
        double valueBlue = 0.0;  
        int valueRGB = 0;  
        int i, j;  
  
        for (i = startX, j = start; i <= stopX; i++, j++) {  
            valueRGB = bufImg.getRGB(i, y);  
  
            valueRed += GetRedValue(valueRGB) * pContrib[j];  
            valueGreen += GetGreenValue(valueRGB) * pContrib[j];  
            valueBlue += GetBlueValue(valueRGB) * pContrib[j];  
        }  
  
        valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen),  
                Clip((int) valueBlue));  
        return valueRGB;  
  
    } // end of HorizontalFilter()  
  
    // 图片水平滤波  
    private BufferedImage HorizontalFiltering(BufferedImage bufImage, int iOutW) {  
        int dwInW = bufImage.getWidth();  
        int dwInH = bufImage.getHeight();  
        int value = 0;  
        BufferedImage pbOut = new BufferedImage(iOutW, dwInH,  
                BufferedImage.TYPE_INT_RGB);  
  
        for (int x = 0; x < iOutW; x++) {  
  
            int startX;  
            int start;  
            int X = (int) (((double) x) * ((double) dwInW) / ((double) iOutW) + 0.5);  
            int y = 0;  
  
            startX = X - nHalfDots;  
            if (startX < 0) {  
                startX = 0;  
                start = nHalfDots - X;  
            } else {  
                start = 0;  
            }  
  
            int stop;  
            int stopX = X + nHalfDots;  
            if (stopX > (dwInW - 1)) {  
                stopX = dwInW - 1;  
                stop = nHalfDots + (dwInW - 1 - X);  
            } else {  
                stop = nHalfDots * 2;  
            }  
  
            if (start > 0 || stop < nDots - 1) {  
                CalTempContrib(start, stop);  
                for (y = 0; y < dwInH; y++) {  
                    value = HorizontalFilter(bufImage, startX, stopX, start,  
                            stop, y, tmpContrib);  
                    pbOut.setRGB(x, y, value);  
                }  
            } else {  
                for (y = 0; y < dwInH; y++) {  
                    value = HorizontalFilter(bufImage, startX, stopX, start,  
                            stop, y, normContrib);  
                    pbOut.setRGB(x, y, value);  
                }  
            }  
        }  
  
        return pbOut;  
  
    } // end of HorizontalFiltering()  
  
    private int VerticalFilter(BufferedImage pbInImage, int startY, int stopY,  
            int start, int stop, int x, double[] pContrib) {  
        double valueRed = 0.0;  
        double valueGreen = 0.0;  
        double valueBlue = 0.0;  
        int valueRGB = 0;  
        int i, j;  
  
        for (i = startY, j = start; i <= stopY; i++, j++) {  
            valueRGB = pbInImage.getRGB(x, i);  
  
            valueRed += GetRedValue(valueRGB) * pContrib[j];  
            valueGreen += GetGreenValue(valueRGB) * pContrib[j];  
            valueBlue += GetBlueValue(valueRGB) * pContrib[j];  
            // System.out.println(valueRed+"->"+Clip((int)valueRed)+"<-");  
            //    
            // System.out.println(valueGreen+"->"+Clip((int)valueGreen)+"<-");  
            // System.out.println(valueBlue+"->"+Clip((int)valueBlue)+"<-"+"-->");  
        }  
  
        valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen),  
                Clip((int) valueBlue));  
        // System.out.println(valueRGB);  
        return valueRGB;  
  
    } // end of VerticalFilter()  
  
    private BufferedImage VerticalFiltering(BufferedImage pbImage, int iOutH) {  
        int iW = pbImage.getWidth();  
        int iH = pbImage.getHeight();  
        int value = 0;  
        BufferedImage pbOut = new BufferedImage(iW, iOutH,  
                BufferedImage.TYPE_INT_RGB);  
  
        for (int y = 0; y < iOutH; y++) {  
  
            int startY;  
            int start;  
            int Y = (int) (((double) y) * ((double) iH) / ((double) iOutH) + 0.5);  
  
            startY = Y - nHalfDots;  
            if (startY < 0) {  
                startY = 0;  
                start = nHalfDots - Y;  
            } else {  
                start = 0;  
            }  
  
            int stop;  
            int stopY = Y + nHalfDots;  
            if (stopY > (int) (iH - 1)) {  
                stopY = iH - 1;  
                stop = nHalfDots + (iH - 1 - Y);  
            } else {  
                stop = nHalfDots * 2;  
            }  
  
            if (start > 0 || stop < nDots - 1) {  
                CalTempContrib(start, stop);  
                for (int x = 0; x < iW; x++) {  
                    value = VerticalFilter(pbImage, startY, stopY, start, stop,  
                            x, tmpContrib);  
                    pbOut.setRGB(x, y, value);  
                }  
            } else {  
                for (int x = 0; x < iW; x++) {  
                    value = VerticalFilter(pbImage, startY, stopY, start, stop,  
                            x, normContrib);  
                    pbOut.setRGB(x, y, value);  
                }  
            }  
  
        }  
  
        return pbOut;  
  
    } // end of VerticalFiltering()  
  
    private int Clip(int x) {  
        if (x < 0)  
            return 0;  
        if (x > 255)  
            return 255;  
        return x;  
    }  
  
    /** 
     * End: Use Lanczos filter to replace the original algorithm for image 
     * scaling. Lanczos improves quality of the scaled image modify by :blade 
     */  
  
}  